Quantum key distribution with correlated sources

TL;DR

This paper presents a general method and a new framework for proving the security of quantum key distribution protocols that involve correlated pulses, addressing practical device imperfections and advancing implementation security.

Contribution

It introduces a simple, general method for security proofs of QKD with long-range pulse correlations and the reference technique framework that encompasses existing proofs.

Findings

Proves security of QKD with arbitrarily long-range correlations.

Compatible with security proofs for various device imperfections.

Framework includes existing security proofs as special cases.

Abstract

In theory, quantum key distribution (QKD) offers information-theoretic security. In practice, however, it does not due to the discrepancies between the assumptions used in the security proofs and the behaviour of the real apparatuses. Recent years have witnessed a tremendous effort to fill the gap, but the treatment of correlations among pulses has remained a major elusive problem. Here, we close this gap by introducing a simple yet general method to prove the security of QKD with arbitrarily long-range pulse correlations. Our method is compatible with those security proofs that accommodate all the other typical device imperfections, thus paving the way towards achieving implementation security in QKD with arbitrary flawed devices. Moreover, we introduce a new framework for security proofs, which we call the reference technique. This framework includes existing security proofs as special cases and it can be widely applied to a number of QKD protocols.